Tapered roller transport mechanism for web of photographic materials and the like

ABSTRACT

The tapered rollers of this web transport mechanism are specifically constructed and arranged to apply driving force to only the marginal edge portions of the web being transported to minimize the possibility of scratching and pressure marking of the central image-bearing sensitized surface of the web and also maintain frictional driving contact without close fitting tolerance between each pair of rollers. The mechanism includes a plurality of pairs of oppositely tapered rollers having opposed surfaces spaced apart a distance slightly greater than the thickness of the web to be transported, the rollers of adjacent pairs being oppositely tapered and arranged to alternately offset the marginal edge portions of the web path defined thereby and produce a zigzag, twisting action on the web to cause the frictional driving pressure to be exerted only on the marginal edge portions of said web and also permit a spacing wider than the web thickness be maintained between each pair of rollers.

United States Patent [191 Lee 9 v [73] Assignee: Pako Corporation,Minneapolis,

Minn.

22 Filed: Aug. 24, 1973 21 Appl. No.: 391,334

[52] U.S. Cl 226/184, 95/89 A, 226/189 [51] Int. Cl. G031! 3/12 [58]Field of Search 226/118, 184, 189, 17,

[56] References Cited UNITED STATES PATENTS 4/1956 Franklin 226/l847/1970 Savela 226/189 X Primary Examiner-Richard A. Schacher Attorney,Agent, or Firm-John W. Adams [111 3,830,419 [451 Aug. 20, 1974 57]ABSTRACT The tapered rollers of this web transport mechanism arespecifically constructed and arranged to apply driving force to only themarginal edge portions of the web being transported to minimize thepossibility of scratching and pressure marking of the centralimagebearing sensitized surface of the web and also maintain frictionaldriving contact without close fitting tolerance between each pair ofrollers. The mechanism includes a plurality of pairs of oppositelytapered rollers having opposed surfaces spaced apart a distance slightlygreater than the thickness of the web to be transported, the rollers ofadjacent pairs being oppositely tapered and arranged to alternatelyoffset the marginal edge portions of the web path defined thereby andproduce a zigzag, twisting action on the web to cause the frictionaldriving pressure to be exerted only on the marginal edge portions ofsaid web and also permit a spacing wider than the web thickness bemaintained between each pair of rollers.

6 Claims, 4 Drawing Figures TAPERED ROLLER TRANSPORT MECHANISM FOR WEBOF PHOTOGRAPHIC MATERIALS AND THE LIKE It has constantly been a problemto provide a transport mechanism for photographic web materials such asfilm and print paper, to prevent surface scratching and pressure markingof the relatively soft photographic surface being processed by theparticular processing equipment through which the transport mechanismcarries the web.

It is an object of the present invention to provide a transportmechanism for photographic equipment which is particularly designed toproduce roller contact pressure along only the marginal edge portions ofthe web of photographic material being transported.

It is another object of the present invention to provide a web transportmechanism including pairs of'oppositely tapered rollers spaced apart adistance greater than the thickness of the web being transported andmounted on opposed parallel axes which define the center line of the webpath therebetween for simplicity of manufacture and application ofdriving motion to the rollers, the edges of the web path throughadjacent pairs of rollers being offset to produce a zigzag, twistingmotion of the web about said center line and thus exert driving pressureon only the marginal edge portions of said web and eliminate rollercontact with the central principal image-bearing area of the web.

These and other objects and advantages of this invention will more fullyappear in the following description made in connection with theaccompanying drawings in which like reference characters refer tosimilar parts throughout the several views, and, in which:

FIG. 1 is a side elevational view of the transport mechanism with theoscillating plate removed;

FIG. 2 is an end elevation of the transport mechanism takensubstantially along the line 22 of FIG. 1;

FIG. 3 is a fragmentary horizontal sectional view taken substantiallyalong the line 3-3 of FIG. 2; and,

FIG. 4 is a fragmentary vertical sectional view taken substantiallyalong the line 4-4 of FIG. 2.

The photographic processor which embodies this invention is best shownin FIG. 1 and includes an outer housing or casing designated by theletter C. The particular processor illustrated includes four separateprocessing tanks respectively designated by the numerals 10, 11, 12 and13. Tanks 10, 11 and 12 each contain a different liquid used in theprocessing system and tank 13 defines a drying chamber. The transportmechansim includes a pair of side panels or plates respectivelydesignated by the numerals I4 and 15.

The transport mechanism includes a plurality of pairs of tapered rollers16. Each roller is mounted for rotation between the plates 14 and 15 onsuitable supporting shafts 17 respectively rotating on axes 17a.

Any suitable means for imparting rotary driving motion to the rollers 17may be provided such as the DRIVING MECHANISM FOR A ROLLER TRANS-PORTING DEVICE disclosed in my U.S. Pat. No. 3,608,807. This mechanismincludes a single oscillating plate (not shown herein) to which aplurality of driving pins 18b are fixed. One shaft 17 of each pair ofrollers has a crank arm 18a fixed in radially outstanding relationthereto and these crank arms 18a are respectively engaged by the crankpins 18b which in turn are driven by said oscillating plate in themanner set forth in said prior patent. Instead of the two oscillatingplates 40 and 42 disclosed in said patent, the present mechanismincludes only one such plate which is designed to drive only one ofeachpair of rollers. In the mechanism disclosed herein, the other roller ineach pair is driven by a pair of meshed gears 19 respectively fixed tothe ends of the shafts l7 opposite to the ends to which the crank armsl8a'are fixed. This is best shown in FIGS. 2 and 3.

As best shown in FIG. 1 the axes of adjacent pairs of rollers areoriented in such a manner to define a continuous web path through theprocessing tanks 10, ll, 12 and 13. A plurality of rollers 16 areprovided which are tapered from one end to the other and the opposedsurfaces thereof are spaced apart a distance greater than the thicknessof a web W of material to be transported. The direction of taper of oneroller in each pair is opposite to the direction of taper of the otherroller in that pair as best shown in FIG. 3. The direction of taper ofeach pair of rollers is opposite to the direction of taper of adjacentpairs of rollers. The web of photographic material W is best shown inFIGS. 3 and 4 which illustrate the zigzag path followed by the marginaledge portions of the web W through the roller train and the photographicprocessing tanks.

The alternating of the direction of taper of adjacent rollers not onlyproduces the zigzag path of the web as described but also maintains theweb in transversely centered relationship along the center line of itsdesired web path. We have found that an even number of pairs oftransport rollers at the curved ends of each loop of the web path servesto maintain the web W in this centered relationship as it passes aroundthe curved portion of the path. It seems to be important that an evennumber of pairs of rollers are provided for carrying the web througheach of the various conditions encountered along the web path to avoidany tendency to cause the web to travel off the center line of the path.

Since the spacing between the rollers of each pair is wider than thethickness of the web being transferred it has been found to be desirableto provide a pair of squeegee rollers 20 at the top of the exit portionof the path in each liquid confining tank. These squeegee rollers 20 arein surface contact and are positioned above the liquid level of each ofthe liquid tanks, 10, 11 and 12. They are of soft yieldable material andare positioned to press against both sides of the web to squeegee offsubstantially all of the liquid from the surface of the web W as it istransported out of each tank.

It will be seen that the opposite orientation of adjacent rollersproduces an offset of both marginal edge portions of the web thuscausing a tensioning of edge portions to provide maximum drive pressuretherealong and eliminate the driving contact pressure on the centralimage-bearing areas of the web. The requirement for close tolerances ofthe spacing between each pair of rollers 17 has also been eliminated.

It will, of course, be understood that various changes may be made inthe form, details, arrangement and proportions of the parts withoutdeparting from the scope of this invention as set forth in the appendedclaims.

What is claimed is:

1. A transport mechanism for elongated webs of sheet material comprisinga roller supporting structure,

a plurality of pairs of tapered transport rollers mounted on saidstructure, the spacing between the rollers of each pair being greaterthan the thickness of the web being transported,

the taper of each roller being opposite to its adjacent rollers and saidrollers being oriented to produce a zigzag path for the marginal edgeportions of a web of material being transported through said rollers,and

means for driving said rollers to produce the movement of such webthrough the spacing between the respective pairs along the desired webpath.

2. The structure set forth in claim I wherein the axes of rotation ofthe rollers are parallel and define the center line of desired web paththerebetween.

3. The structure set forth in claim 2 and said web path having a numberof U-shaped loops with an even number of pairs of rollers disposed atthe closed curved portion of each loop.

4. The structure set forth in claim 2 and the number of pairs of rollersfor all of the respective conditions encountered along the web pathbeing an even number to avoid any tendency of the tapered rollers tomove the web off the center line of its desired path.

5. The structure set forth in claim 1 and a number of liquid confiningtanks through which the web is transported and a pair of soft yieldablesqueegee rollers at the exit end of each tank to remove substantiallyall of the liquid from the web surfaces.

6. The structure set forth in claim 1 and adjacent pairs of rollersbeing oriented to produce a web path center portion through which asubstantial central image-bearing area of the web is free from contactwith said rollers, the web diagonally transversing the width of thespace between each pair of rollers with the marginal edge portion of oneside of the web in frictional driving contact with a larger portion ofone of said rollers and the marginal edge portion of the other side ofthe web in frictional driving contact with a larger portion of the otherroller of each pair.

1. A transport mechanism for elongated webs of sheet material comprisinga roller supporting structure, a plurality of pairs of tapered transportrollers mounted on said structure, the spacing between the rollers ofeach pair being greater than the thickness of the web being transported,the taper of each roller being opposite to its adjacent rollers and saidrollers being oriented to produce a zigzag path for the marginal edgeportions of a web of material being transported through said rollers,and means for driving said rollers to produce the movement of such webthrough the spacing between the respective pairs along the desired webpath.
 2. The structure set forth in claim 1 wherein the axes of rotationof the rollers are parallel and define the center line of desired webpath therebetween.
 3. The structure set forth in claim 2 and said webpath having a number of U-shaped loops with an even number of pairs ofrollers disposed at the closed curved portion of each loop.
 4. Thestructure set forth in claim 2 and the number of pairs of rollers forall of the respective conditions encountered along the web path being aneven number to avoid any tendency of the tapered rollers to move the weboff the center line of its desired path.
 5. The structure set forth inclaim 1 and a number of liquid confining tanks through which the web istransported and a pair of soft yieldable squeegee rollers at the exitend of each tank to remove substantially all of the liquid from the websurfaces.
 6. The structure set forth in claim 1 and adjacent pairs ofrollers being oriented to produce a web path center portion throughwhich a substantial central image-bearing area of the web is free fromcontact with said rollers, the web diagonally transversing the width ofthe space between each pair of rollers with the marginal edge portion ofone side of the web in frictional driving contact with a larger portionof one of said rollers and the marginal edge portion of the other sideof the web in frictional driving contact with a larger portion of theother roller of each pair.